package com.zjm.structural.facade;

public class Screen {
    // 饿汉式单例模式
    private static final Screen instance = new Screen();

    private Screen() {

    }

    public static Screen getInstance() {
        return instance;
    }

    public void up() {
        System.out.println("Screen UP");
    }

    public void down() {
        System.out.println("Screen DOWN");
    }
}
